The invention belongs to the technical field of near-eye display, and particularly relates to a near-eye display device, a preparation method and wearable equipment.
Disclosure of Invention
The invention at least partially solves the problem of limited viewing angle of the existing near-eye display device and provides a near-eye display device with larger viewing angle.
The technical scheme adopted for solving the technical problem of the invention is a near-eye display device, which comprises:
a display panel;
a superlens unit located on a light exit surface side of the display panel; the superlens unit includes: the liquid crystal display device comprises a liquid crystal structure and a micro-nano structure layer, wherein liquid crystal molecules in the liquid crystal structure can deflect, so that the focus of the super lens unit can move in a first range;
the focal point of the superlens unit falls within the plane of the panel.
In some embodiments, the superlens unit includes: the first electrode layer and the second electrode layer are oppositely arranged; the first electrode layer comprises at least one first electrode disposed on a first substrate; the second electrode layer comprises at least one second electrode disposed on a second substrate;
the liquid crystal layer and the micro-nano structure layer are positioned between the first electrode layer and the second electrode layer;
liquid crystal molecules in the liquid crystal layer are deflected under the driving of an electric field between the first electrode and the second electrode, so that the focus of the super lens unit is moved.
In some embodiments, the superlens unit includes a plurality of superlens unit pixels; the first electrode, the second electrode, liquid crystal molecules and the micro-nano structure are arranged in each super-lens unit pixel;
the second electrode layer comprises a plurality of second electrodes, and each second electrode corresponds to one super-lens unit pixel.
In some embodiments, the first electrode in a plurality of the superlens unit pixels is a unitary structure.
In some embodiments, the distance between the first electrode layer and the second electrode layer comprises: 2-3 microns.
In some embodiments, the micro-nano structure layer comprises: a plurality of nano-pillars arranged in an array.
In some embodiments, the material of the nanopillars comprises: at least one of silicon nitride, titanium dioxide, gallium nitride, silicon.
In some embodiments, the display panel includes: an optical fiber scanning display.
In some embodiments, the near-eye display device further comprises a control circuit for writing a first control signal to the first electrode and writing a second control signal to the second electrode to cause the liquid crystal molecules to deflect under the driving of an electric field between the first electrode and the second electrode.
The technical scheme adopted for solving the technical problem of the invention is wearable equipment, wherein the wearable equipment comprises any one near-to-eye display device.
The technical scheme adopted for solving the technical problem of the invention is a preparation method of a near-eye display device, which comprises the following steps:
providing a display panel;
providing a first substrate, and forming a first electrode layer on the first substrate;
providing a second substrate, and forming a second electrode layer on the second substrate;
forming a micro-nano structure layer on the first substrate or the second substrate;
aligning the first substrate and the second substrate; the surface of the first substrate, on which the first electrode layer is formed, faces the surface of the second substrate, on which the second electrode layer is formed;
a liquid crystal layer is formed between the first electrode layer and the second electrode layer.
Detailed Description
In order to make the technical solutions of the present invention better understood, the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
In the present invention, the two structures "in the same layer" means that they are formed of the same material layer and thus are in the same layer in a stacked relationship, but do not represent that they are equidistant from the substrate nor that they are completely identical in structure with other layers between the substrate.
In the present invention, the "patterning process" refers to a step of forming a structure having a specific pattern, which may be a photolithography process including one or more steps of forming a material layer, coating a photoresist, exposing, developing, etching, stripping a photoresist, and the like; of course, the "patterning process" may also be an imprinting process, an inkjet printing process, or other processes.
The invention will be described in more detail below with reference to the accompanying drawings. Like elements in the various figures are denoted by like reference numerals. For purposes of clarity, the various features in the drawings are not necessarily drawn to scale. Moreover, certain well-known elements may not be shown in the figures.
In the following description, numerous specific details of the invention, such as structure, materials, dimensions, processing techniques and techniques of components, are set forth in order to provide a more thorough understanding of the invention. However, as will be understood by those skilled in the art, the present invention may be practiced without these specific details.
The super-surface serves as an important platform in novel planar optics. And the nanostructure array distribution of the sub-wavelength level remodels the target electromagnetic wave front. Superlens units have been widely studied to address the challenges of conventional optics and show significant potential in practical applications. Unlike conventional lenses, superlens cells are optically thick and very light, do not require complex refractive optics to control phase, amplitude, and polarization, and have high numerical apertures. The overall fabrication may be based on a semiconductor CMOS process.
The development of near-eye display (including AR/VR, etc.) technology is limited by the ability of the eyepiece to display due to its bulkiness, weight, and compromise. The super lens unit combined with the advantages of super small size, high resolution, high dynamic modulation range and the like can be well applied to a near-eye display system. For example, current designs are based on superlens units combined with fiber scanning technology for displaying complex and large-sized graphics larger than the focal range. However, the currently designed superlens unit has a fixed focus, the field of view (FOV) of the near-eye display device depends heavily on NA (numerical aperture), if the NA needs to be increased as much as possible, the complexity of the structural design is undoubtedly increased, and the improvement capability of the field of view through the NA is limited.
In view of the above technical problems, referring to fig. 1 to 7c, in one aspect, the present embodiment provides a near-eye display device, including: a display panel and a superlens unit 01. The superlens unit 01 is located on the light exit surface side of the display panel. The superlens unit 01 includes: the liquid crystal display device comprises a liquid crystal structure and a micro-nano structure layer, wherein liquid crystal molecules in the liquid crystal structure can deflect, so that the focus of the superlens unit 01 can move in a first range; the focal point of the superlens unit 01 falls within the plane of the panel.
In some embodiments, a display panel includes: an optical fiber scanning display. Referring to fig. 1, in the Fiber scanning display portion, a Laser beam (Laser) is collimated by a Fiber coupled collimator (Fiber coupled collimator) and then passes through an AOM acousto-optic modulator for modulating a generated beam within a specific time intensity of an incident beam. The modulated beam is coupled into one end of the fiber by a Coupling lens. The coupled beam is transmitted through the optical fiber to the other end. The other end of the fiber is fixed to a piezoelectric tube (Piezo tube) for controlling the spatial movement of the fiber tip. The piezoelectric tube and the piezoelectric drive (Piezo drive) are connected by orthogonal electrodes. The spatial motion of the fiber head and the time intensity modulation of the incident beam are synthesized by a data center, which consists of a pc (pc master), data acquisition and I/O connectors. The PC is used for image processing and converting display into input signals for the acousto-optic modulator and the piezoelectric drive. The input signal is distributed to the hardware through the data acquisition card and the I/O connector. A design display reflected by a picture is displayed on a plane through optical fiber scanning. The scan plane will be placed at the focal plane of the superlens unit 01(Metalens) and a magnified virtual picture will be formed at a distance from the superlens unit 01 so that the virtual picture will be seen by the eye.
Referring to fig. 2, the superlens unit 01 is located on the Display side of the Display (Display), and the focal point of the superlens unit 01 falls within the plane of the Display. The size of the superlens unit 01 depends on the focal length and numerical aperture NA:
Ddisplay≈DML=2FMLtan(sin-1NA)
wherein D isdisplayTo the size of the display, DMLIs the size of the superlens unit 01, FMLIs the focal length of the superlens unit 01. The size of the superlens unit 01 should be equal to the size of the display, or the size of the superlens unit 01 is slightly larger than the size of the display, so as to ensure that the picture can be displayed completely. It is assumed that the distance between the eye and the superlens unit 01 will be defined as an eye comfort zone dr. To be able to capture the entire virtual image, drThe following equation relationship must be satisfied:
wherein D iseyeboxEye ball size, DMLIs a size of the super lens unit 01, thetamaxIs the maximum system field angle (FOV). The field angle is related to the NA of the superlens unit 01 as follows:
θ=2sin-1NA
that is, in the case where the focal length of the superlens unit 01 is fixed, NA plays a key role in the angle of field, and the size of the superlens unit 01 needs to be larger than the display size. In order to realize a VR system with a large FOV and a small planar factor, it is necessary to design a high NA optical eyepiece so that the near-eye display device has a high image quality display and a high resolution micro-display. If the NA is directly increased, the difficulty of designing the superlens unit 01 is increased, and the increase of the field angle is limited.
In the near-eye display device provided in the present embodiment, the superlens unit 01 includes: the liquid crystal display device comprises a liquid crystal structure and a micro-nano structure layer, wherein liquid crystal molecules in the liquid crystal structure can deflect, so that the focus of the superlens unit 01 can move in a first range; the focal point of the superlens unit 01 falls within the plane of the panel. The micro-nano structure layer has the main function of realizing phase distribution with a fixed focal length. The liquid crystal unit plays a tuning role, under an external voltage, the polarization angle of liquid crystal molecules rotates, the output phases of the liquid crystal unit are different, and the phase modulation and the micro-nano structure layer are superposed to determine the final phase output of the super lens unit 01. Specifically, the electric field near the liquid crystal molecules can be controlled to drive the liquid crystal to deflect, so that the phase of the superlens unit 01 is changed in sound. Referring to fig. 5, in the case of light with a wavelength of 530nm, the micro-nano structure layer is formed by nano-pillars with a diameter of 150nm and a height of 600nm, and when the light passes through the superlens unit 01, the phase changes when the refractive index changes from 1.5 to 1.7 by controlling the liquid crystal deflection. Preferably, the cell thickness of the liquid crystal structure is 2.7 microns to achieve 360 ° phase modulation, thereby ensuring that the superlens cell 01 array is capable of achieving light focusing and subsequent dynamic regulation of the focal position. In this embodiment, the focal point position change is a change in the focal point movement of the superlens unit 01 without changing the focal length thereof, that is, the focal point moves within a plane. In the embodiment, although the focal length of the super-lens unit is inconvenient and NA is not changed, as the focal point moves, the image range seen by human eyes also moves, that is, the field angle moves, so that the field angle of the near-eye display device is changed from a single fixed field angle to a movable variable field angle, the field angle of the near-eye display device is increased, and the display effect of the near-eye display device is improved. That is to say, in the present embodiment, the phase change of the liquid crystal structure is controlled, so that the focal point of the superlens unit 01 can be moved within a certain range, and further, the reconstruction of the point detection position of the superlens unit 01 is realized without changing the superlens unit 01NA, the field angle of the near-to-eye display device is effectively increased, and the display effect thereof is improved.
In some embodiments, referring to fig. 4, the superlens unit 01 includes: a first electrode layer 11 and a second electrode layer 21 which are oppositely arranged; the first electrode layer 11 includes at least one first electrode disposed on the first substrate 10; the second electrode layer 21 includes at least one second electrode disposed on the second substrate 20; the liquid crystal layer 5 and the micro-nano structure layer are positioned between the first electrode layer 11 and the second electrode layer 21; liquid crystal molecules in the liquid crystal layer 5 are deflected by an electric field between the first electrode and the second electrode to move the focus of the superlens unit 01. In this embodiment, a control electric field is formed between the first electrode and the second electrode by applying corresponding control voltages to the first electrode and the second electrode, thereby controlling the liquid crystal to deflect. The micro-nano structure 3 is disposed in a liquid crystal cell to form the superlens unit 01, so that the phase of the superlens unit 01 is changed by the deflection of the liquid crystal, and the focal position thereof is changed.
In some embodiments, referring to FIG. 3, a
superlens cell 01 includes a plurality of
superlens cell 01 pixels; a first electrode, a second electrode, liquid crystal molecules and a
micro-nano structure 3 are arranged in each
super-lens unit 01 pixel; the
second electrode layer 21 includes a plurality of second electrodes, each corresponding to a
superlens unit 01 pixel. The first electrode may be a common electrode, and the second electrode may be a pixel electrode. When the liquid crystal driving circuit works, a common electric signal is written into each first electrode in each
super lens unit 01 pixel, and a driving electric signal is written into each second electrode, so that independent adjustment of liquid crystal driving in each
super lens unit 01 pixel is realized. By changing the driving signal, it can be realized that the phase of each
superlens unit 01 pixel is changed within the range of 0-360 °. On the basis, the corresponding relation between the driving voltage and the phase change of each
super lens unit 01 pixel in the
super lens units 01 and the relation between the pixel phase of each
super lens unit 01 and the focus position of the
super lens unit 01 are determined, so that the focus position change of the
super lens unit 01 is controlled according to the driving voltage of each
super lens unit 01 pixel, and the focus position reconstruction of the
super lens unit 01 is realized. Specifically, referring to FIGS. 6-7c, the phase of the
superlens unit 01 pixels is related to the
superlens unit 01 focal position
Where r is the radial position corresponding to the coordinates of the
superlens unit 01 pixels,
to correspond to the phase of
superlens unit 01, λ
iIs the target wavelength of light, r
offsetIs the focus bias of the superlens unit 01Amount of shift, f is focal length, x
offsetAmount of shift of focal point in x-axis direction, y
offsetThe shift amount of the focal point in the y-axis direction. That is, in the present embodiment, by adjusting the phase of some or all of the pixels of the
superlens unit 01, the dynamic focus movement change of the
superlens unit 01 can be realized. In addition, as described above, the phase change of the pixels of the
superlens unit 01 can be achieved by controlling the liquid crystal to be deflected by a corresponding angle according to the applied driving voltage.
In some embodiments, the first electrodes in the plurality of superlens unit 01 pixels are a unitary structure. In this embodiment, under the condition that each second electrode corresponds to each superlens unit 01 pixel, the same electrical signal can be written into the first electrode of each superlens unit 01 pixel, and at this time, the plurality of first electrodes can be integrated into one structure, so as to simplify the manufacturing process and reduce the manufacturing cost.
In some embodiments, the distance between the first electrode layer 11 and the second electrode layer 21 includes: 2-3 microns.
In some embodiments, the superlens unit 01 further includes: and a pixel dividing part for separating liquid crystal molecules between two adjacent super lens unit 01 pixels by the pixel separating part so as to independently control the liquid crystal deflection degree in each super lens unit 01 pixel. It is understood that the liquid crystal deflection is mainly controlled by the surrounding electric field, and in this embodiment, the pixel division portion is not provided, and the liquid crystal molecules at the corresponding positions are directly driven to deflect by the voltage change of the pixel electrodes.
In some embodiments, the near-eye display device further comprises a control circuit (Volt control system) for writing a first control signal to the first electrode and a second control signal to the second electrode to cause the liquid crystal molecules to deflect under the drive of an electric field between the first electrode and the second electrode. Wherein, each first control signal can be the same and is a public electric signal; each second control signal is a driving electric signal required for the liquid crystal deflection of the pixel of each superlens unit 01. By writing corresponding electrical signals to the first and second electrodes, the liquid crystal in each superlens unit 01 pixel can be controlled to deflect in response so that the focus of the superlens unit 01 moves to the corresponding position.
In some embodiments, the micro-nano structure layer comprises: a plurality of nano-pillars arranged in an array. In this embodiment, an ultra-thin two-dimensional array plane can be formed by a series of sub-wavelength artificial microstructures (nano-pillars), so that the superlens unit 01 has the characteristics of relatively simple manufacture, relatively low loss, small volume, thin thickness and the like. By utilizing specification selection and setting of the nano-columns, flexible and effective regulation and control on the aspects of amplitude, phase, propagation mode, polarization state and the like of electromagnetic waves can be realized. The nano-pillars are nano-scale columnar structures with different radii at two ends, and the material of the nano-pillars generally comprises at least one of silicon nitride (Si3N4), titanium dioxide (TiO2), gallium nitride and silicon. Referring to fig. 1, in the microlens, a superlens unit 01 satisfying a light convergence requirement is formed by arranging a plurality of nano-pillars having different aspect ratios and by designing orientations of wide ends and narrow ends of the nano-pillars. Specifically, in the microlens, the nano-pillars may be arranged alternately in a mixed manner of a positive and a negative structure. The positive and negative structure is to distinguish the nano-pillar with the wide end near the substrate from the nano-pillar with the narrow end near the substrate, one of the two nano-pillars with different arrangement modes can be regarded as the positive structure, and the other nano-pillar can be regarded as the negative structure. The depth-to-width ratio of the nano-pillars serving as the positive structures or the negative structures can also be different when the positive and negative structures are mixed and arranged alternately. The setting can be carried out according to different requirements.
On the other hand, the present embodiment further provides a wearable device, including the near-eye display apparatus provided in the above embodiments; in addition, the wearable device further comprises a housing on which the near-eye display device is disposed. The shell may be a helmet, an eyeglass frame, or the like.
On the other hand, referring to fig. 5, the present embodiment provides a method for manufacturing a near-eye display device, which can be used to manufacture any of the above-mentioned near-eye display devices. The preparation method comprises the following steps:
and S1, providing a display panel. Wherein the display panel may comprise a fiber optic scanning display.
S2, providing the first substrate 10, and forming the first electrode layer 11 on the first substrate 10. The material of the first substrate 10 may include silicon oxide, silicon nitride, silicon oxynitride, and the like. The material of the first electrode layer 11 may include a transparent conductive material such as Indium Tin Oxide (ITO). In this embodiment, the first electrode layer 11 may be formed on the first substrate 10 by a process such as sputtering.
S3, providing the second substrate 20, and forming the second electrode layer 21 on the second substrate 20. The material of the second substrate 20 may include silicon oxide, silicon nitride, silicon oxynitride, and the like. The material of the second electrode layer 21 may include a transparent conductive material such as Indium Tin Oxide (ITO). In this embodiment, the second electrode layer 21 may be formed on the second substrate 20 by a process such as sputtering.
And S4, forming a micro-nano structure layer on the first substrate 10 or the second substrate 20. The micro-nano structure layer may be disposed on one of the first substrate 10 and the second substrate 20.
Optionally, in some embodiments, the method further comprises a step of forming the liquid crystal alignment layer 5. The liquid crystal alignment layer 5 is used for carrying out initial alignment on liquid crystal molecules and ensuring the arrangement consistency of the liquid crystal molecules.
S5, aligning the first substrate 10 and the second substrate 20; the surface of the first substrate 10 on which the first electrode layer 11 is formed faces the surface of the second substrate 20 on which the second electrode layer 21 is formed.
S6, the liquid crystal layer 5 is formed between the first electrode layer 11 and the second electrode layer 21. In this step, the liquid crystal layer 5 may be formed between the first electrode layer 11 and the second electrode layer 21 by the direction of liquid crystal injection.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
While embodiments in accordance with the invention have been described above, these embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments described. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. The invention is limited only by the claims and their full scope and equivalents.